Negative electrode active material for non-aqueous electrolyte secondary battery, method for producing same

Abstract

A negative electrode active material for a non-aqueous electrolyte secondary battery containing negative electrode active material particles which include silicon compound particles containing a silicon compound (SiO x : 0.5≤x≤1.6), wherein the silicon compound particles are a negative electrode active material for a non-aqueous electrolyte secondary battery containing a Li compound, the material particles are at least partially coated with a carbon coating, an amount of the carbon coating relative to a total amount of the silicon compound particles and carbon coating is larger than 0 mass % and 1 mass % or less, the carbon coating contains a coating composed of at least any one of a compound having O—C═O bond and a compound having C—C bond, and the silicon compound particles contain crystalline Li 2 SiO 3 as the Li compound. Thereby, the negative electrode active material for a non-aqueous electrolyte secondary battery having a large capacity, excellent cycle characteristics, and first-time efficiency is provided.

1 - 19 . (canceled) 
     
     
         20 . A negative electrode active material for a non-aqueous electrolyte secondary battery containing negative electrode active material particles in which the negative electrode active material particles comprise silicon compound particles containing a silicon compound (SiO x : 0.5≤x≤1.6), wherein
 the silicon compound particles are a negative electrode active material for a non-aqueous electrolyte secondary battery containing a Li compound, 
 the negative electrode active material particles are at least partially coated with a carbon coating, 
 an amount of the carbon coating on the negative electrode active material particles relative to a total amount of the silicon compound particles and the carbon coating is larger than 0 mass % and 1 mass % or less, 
 the carbon coating contains a coating composed of at least any one of a compound having O—C═O bond and a compound having C—C bond, and 
 the silicon compound particles contain crystalline Li 2 SiO 3  as the Li compound. 
 
     
     
         21 . The negative electrode active material for a non-aqueous electrolyte secondary battery according to  claim 20 , wherein
 the negative electrode active material has an intensity ratio of 0≤Ia/Ib≤3.0 where an intensity Ia around 290 eV is attributable to the O—C═O bond and an intensity Ib around 285 eV is attributable to the C—C bond both obtained by an X-ray photoelectron spectroscopy.   
     
     
         22 . The negative electrode active material for a non-aqueous electrolyte secondary battery according to  claim 20 , wherein
 the negative electrode active material satisfies 1≤Ie/Ic≤18.5 with an intensity Ie around 20=18.7° attributable to Li 2 SiO 3  compared to an intensity Ic around 2θ=47.5° attributable to Si, as obtained by an X-ray diffraction.   
     
     
         23 . The negative electrode active material for a non-aqueous secondary battery according to  claim 22 , wherein
 a peak around 2θ=18.7° attributable to Li 2 SiO 3  obtained by the X-ray diffraction of the negative electrode active material has a half-value width of 0.5° or more and 3.0° or less.   
     
     
         24 . The negative electrode active material for a non-aqueous secondary battery according to  claim 20 , wherein
 a crystallite size attributable to a Si(220) crystal face obtained by the X-ray diffraction of the negative electrode active material is 5 nm or less.   
     
     
         25 . The negative electrode active material for a non-aqueous secondary battery according to  claim 20 , wherein
 the negative electrode active material has at least one or more peaks in at least one region given as chemical shift values of a region of −80 ppm or more and less than −70 ppm, a region of −70 ppm or more and less than −60 ppm, and a region of −60 ppm or more and less than −30 ppm, which are obtained from a  29 Si-MAS-NMR spectrum of the negative electrode active material.   
     
     
         26 . The negative electrode active material for a non-aqueous secondary battery according to  claim 25 , wherein
 peak intensity ratios If/Ii and Ih/li obtained from the  29 Si-MAS-NMR spectrum of the negative electrode active material satisfy both 0≤If/Ii≤0.23 and 0≤Ih/Ii≤1.1, where   If represents a peak intensity of the peak obtained as the chemical shift value in the region of −60 ppm or more and less than −30 ppm,   Ih represents a peak intensity of the peak obtained as the chemical shift value in the region of −70 ppm or more and less than −60 ppm, and   Ii represents a peak intensity of the peak obtained as the chemical shift value in the region of −80 ppm or more and less than −70 ppm.   
     
     
         27 . The negative electrode active material for a non-aqueous electrolyte secondary battery according to  claim 20 , wherein
 an intensity ratio Id/Ig of a D band and a G band in Raman spectrometry of the negative electrode active material is 0≤Id/Ig≤2.0.   
     
     
         28 . The negative electrode active material for a non-aqueous electrolyte secondary battery according to  claim 20 , wherein
 an intensity ratio ISi/Ig of a peak intensity of Si and a G band in Raman spectrometry of the negative electrode active material is 0≤ISi/Ig≤5.0.   
     
     
         29 . The negative electrode active material for a non-aqueous electrolyte secondary battery according to  claim 20 , wherein
 the silicon compound particles have a median diameter of 0.5 μm or more and 20 μm or less.   
     
     
         30 . The negative electrode active material for a non-aqueous electrolyte secondary battery according to  claim 20 , wherein
 the negative electrode active material particles either do not contain Li 2 CO 3 ; or a portion of an outermost surface of the particle is coated with crystalline Li 2 CO 3 , in addition, the negative electrode active material satisfies 0≤Ij/Ic≤10 with a peak intensity Ij around 2θ=21° attributable to Li 2 CO 3 , compared to an intensity Ic around 2θ=47.5° attributable to Si, as obtained by the X-ray diffraction.   
     
     
         31 . The negative electrode active material for a non-aqueous electrolyte secondary battery according to  claim 20 , wherein
 the negative electrode active material is coated with a carbon layer that is different from the carbon coating.   
     
     
         32 . The negative electrode active material for a non-aqueous electrolyte secondary battery according to  claim 20 , wherein
 the negative electrode active material is coated with the carbon coating which has a peak attributable to the G band in Raman spectrometry of the negative electrode active material in a range of 1588 cm −1  to 1598 cm −1 .   
     
     
         33 . A non-aqueous electrolyte secondary battery comprising the negative electrode active material for a non-aqueous electrolyte secondary battery according to  claim 20 . 
     
     
         34 . A mobile terminal comprising the non-aqueous electrolyte secondary battery according to  claim 33 . 
     
     
         35 . An electric vehicle comprising the non-aqueous electrolyte secondary battery according to  claim 33 . 
     
     
         36 . A power storage system comprising the non-aqueous electrolyte secondary battery according to  claim 33 . 
     
     
         37 . A method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery containing negative electrode active material particles, the method comprising steps of:
 preparing silicon compound particles containing a silicon compound (SiO x : 0.5≤x≤1.6);   inserting Li into the silicon compound particles to produce Li 2 SiO 3  as a Li compound; and   further coating at least part of the silicon compound particles with carbon coating either simultaneously with or following inserting Li into the silicon compound particles, wherein   the negative electrode active material particles are carbon-coated so as to make an amount of carbon coating larger than 0 mass % and 1 mass % or less relative to a total amount of the silicon compound particles and a carbon coating, and the carbon coating composed of at least any one of a compound having O—C═O bond and a compound having C—C bond.   
     
     
         38 . The method for producing a negative electrode active material for a non-aqueous electrolyte secondary battery according to  claim 37 , wherein
 the step of inserting Li into the silicon compound particles is performed by either an electrochemical method or a method by a redox reaction.